You'd think, with all the knee scoping and ACL and MCL surgeries, etc., that doctors know every little part of the human knee. Wrong.

Doctors in Belgium discovered the "anterolateral ligament," or ALL, which 97% of us have. If that rips, you get a "pivot" problem. Fixing an ACL doesn't solve this. They don't yet know how to fix an ALL, which, you know, makes sense, since they only just discovered it -- although it was first theorized by some doctor over 100 years ago.

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so pardon my naivity, but how is it possible that we just discovered this? Haven't we been dissecting human bodies and working on knees for years and years and years? Seems like someone would have noticed...

I'm obviously wrong, but that was my gut reaction when I first heard this. Any MDs want to explain?

Someone showed me this article yesterday. When you look at the picture, the theorized ligament is no small thing! Having dissected the entire human body, this certainly came as a surprise to me. With how much concentration is put into knee surgery I am completely baffled with how this has not been discovered before. I would love to hear more about this.

Anatomist here. It's probably worth pointing out that this bit of tissue has been known about for a very long time (like 19th century). Ligaments are often just thickening in the wall of a joint capsule, and there is disagreement over whether it's actually a distinct structure or just part of another structure (in this case the LCL).

This does seem sufficiently distinct to me, so I'm betting it sticks, but this is not a case of a wholly unknown structure being "discovered" in the sense that word might evoke. It's also possible another research team will publish a paper explaining why they don't think it's really a distinct structure, and round and round we go.

I have also made a rather remarkable discovery with the human body that up till now I had decided to hold back on announcing. I have discovered a thing I shall call "farts". I discovered this rather humorous human condition last night after eating a large bowl of Whitey's original chili with beans for dinner last night along with their Atomic Burger.

First, this looks legit, although I agree it's hard to believe. Published in a peer-reviewed scientific journal.

Second, I agree with Profwoot, and would take his points one step further. I suspect the pictures are deceiving. I suspect that visually and radiographically this ligament is indistinguishable from other structures that it is physically attached to... joint capsule, LCL, ITB, etc. Yet, when you "dissect out" a structure, you are typically clearing all of those structures away... leaving us with a picture that gives the impression of "why the hell didn't we see that before?"

Surgically, we are talking about the lateral aspect of the knee, which is the least often injured, and, subsequently, least operated on portion of the knee (how many times have you heard of an LCL tear? Exactly.). Plus, it sounds as though this structure is quite deep... (layer III) underlying the ITB insertion, and I can't think of any reason anyone would be cutting the ITB to get underneath it... subsequently, this area would go unexplored in the vast majority of knee surgeries. I Think a better question is why haven't radiologists noticed this on the millions of knee MRIs that have been done? But I suspect the answer is as above... when not dissected out, it's likely to be radiographically indistinguishable from the surrounding structures.

It does strike me as odd that this has made it as far as the lay press, and yet none of the authors or reporters are addressing the obvious question of why this is billed as a new discovery.

And thank you OP, for letting me post something that has nothing to do with th efootball team.

(other than, he said "Lay!" yuk-yuk) is that things are frequently taken out of context. A few years back there was all this coverage about the "flesh-eating" bacteria, but if I remember correctly that particular year there were actually fewer cases of necrotizing fasciitis than the historical average.

While human dissection has been going on for centuries, the practical application of those observations have only been recently possible - and it is that practical knowledge which then helps confirm or disprove notions observed in dissections.

Consider that for very long time, the nerves which are linked to potency were theorized to be in a certain location but in the 1970's Pat Walsh, a urologist revisited this topic as part of his effort to develop a potency sparing (nerve sparing) prostatectomy for men with prostate cancer. Sometimes the way dissections are done can also affect the interpretation. There is a congenital condition in some baby boys where they are born with an partially obstructed urethra (posterior urethral valves) - the original dissections and report from 1913 were done on specimens cut longitudinally through the urethra; later anatomists realized that this approach may have distored the impression of the valve leaflets because what was described seemed to vary from what was visible on endoscopy - scopes small enough didn't exist until half a century later.

So, could there be a "new" ligament - yes, but it is probably a better understanding of an existing structure.

Longshot time...for any of you with knowledge here, I injured my knee years ago and no one has been able to explain whats going on. I was kneeling, or more like I was sitting on my shins (knee at full flexion; heel touching my butt) when it felt like my knee almost dislocated and my leg shifted laterally to the outside. I stood up and tried to straighten my leg, but my knee felt locked. Finally with some force, I got it to move with a huge, audible pop, which was extremely painful and left the whole joint feeling lax, but got it better with time. From that point on, its gotten easier and easier to get the knee to pop in and out when kneeling. I've had an MRI which showed a mild tear in my LCL, and then I got scoped, which showed a lot of inflammation and aggravation, but no distinct sign of "injury". Now years later, my other knee has started the popping thing without any sort of injury like there was with the first one. Do I just have junk knees, or do I maybe have F-ed up anterolateral ligaments?